<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        html,
        body {
            width: 100%;
            height: 100%;
            padding: 0;
            margin: 0;
            background-color: #efefef;
        }

        .box {
            width: 600px;
            margin: 50px auto;
        }
        .box-cont{
            padding: 10px;
            height: 500px;
            background-color: #fff;
        }
    </style>
</head>

<body>
    <div class="box">
        <div class="box-cont">121232</div>
    </div>
</body>

</html>